Improvement in jack-screws



R. PJELLMAN.

Jack-Screw.

' No. 222,028. Patented Nov. 25,1879.-

UNITED STATES PATENT OFFICE.

ROBERT FJELLMAN, OF ST. PAUL, MINNESOTA, ASSIGNOR' OF ONE-THIRD OF HISRIGHT TO WILLIAM PFAENDEE, JR, OF SAME PLACE.

IMPROVEMENT IN JACK-SCREWS.

Specification forming part of Letters Patent No. 222,028, dated November25, 1879 application filed July 21, 1879.

of Minnesota, have invented certain new and.

useful Improvements in JackScrews; and I do hereby declare that thefollowing is a full, clear, and exact description of the invention,which willenable others skilled in the art to which it appertains tomake and use the same, reference being had to the accompanying drawings,which form a part of this specification, and in wbich- Figure 1 is aside elevation. Fig. 2 is a ver; tical section. Fig. 3 is a plan or topview. Fig. 4 is a cross-section on line :10 ac, Fig. 2; and Fig. 5.is adetail view of one of the operating-bands detached.

Similar letters of reference indicate corresponding parts in all thefigures.

This invention relates to that class of lifting implements known asjack-screws; and it consists in the combination, with the screw, movingvertically in a threaded socket, of a set of flexible bands, the twoprojecting ends et, which has a sorewthreaded collar, a, at its upperend, into which works the screw B. This is made with a solid head orpost, 0, having an annular flange or shoulder, b, at its lower end, andan offset, 0, at its upper end, forming a pivot, D, upon which thecentrallyperforated movable head E is inserted, bearing with its lowerend against the offset or shoulder c.

F G are two flexible bands, made, preferably, of steel or malleableiron, which are inserted upon the cylindrical head 0 and separated by awasher, H. The two ends of each of these bands are made thickerthan theband itself, and project, parallel to each other, tangentially to oneside, as shown in the drawings, and are united by set-screws, (denotedby f g,'respectively,) which are provided with thumb-nuts, for thepurpose of enabling the operator to regulate the tension of the bands.The two projecting ends or shanks F G of these bands are furtherperforated, as shown at h, to admit of the insertion of one end of theoperating-lever I.

From the foregoing description, taken in connection with the drawings,the operation of my invention will be readily understood. The bands F Gare first adjusted upon the head 0, with their projecting ends pointingtoward each other, as will be seen by reference to Fig. 3, so as toallow them to slip round with case. If it is desired to raise the screw,lever I is inserted into the perforation h of the upper shank,'F, andturned in the direction of the arrow, when the band F will bind aroundthe. head and turn this, thus raising the screw in its socket. Byinserting the lever into the perforated shank of the lower band, G, andturning it in the opposite direction, the screw will be lowered.

The lever being in both cases worked upon one side of and not insertedinto the head gives a better purchase and makes a stronger head, asthere are no perforations to weaken it by the removal of metal. Theparts are not liable to break or give, as in devices of this class whichare operated by a pawl-and-ratohet movement, and the'arrangement of thebands and lever permits this device to be operated with advantage wherethe space for working the lever is limited.

The whole apparatus is exceedingly simple and compact in itsconstruction, making it very strong and durable, which is a desideratumin this class of implements, which are calculated to sustain heavyweights and are often subjected to rough usage.

Having thus described my invention, I claim and desire to secure byLetters Patent of the United States 1. The combination, with thestandard or socket A and screw B, having solid cylindrical head or post0 and shoulder 11, of the adjustable clamping-bands F G, provided withprojecting perforated shanks F G, pointing toward each other,substantially as and for the purpose shown and set forth. I

2. In a jack-screw, the combination, .with the screw B, provided withthe solid cylindri- In testimony that I claim the foregoing as my own Ihave hereto affixed my signature in presence of two witnesses.

ROBERT FJELLMAN.

Witnesses i I E. G. BELL, J OHN A. HIGGINS.

